This invention relates to a method of laundering clothing and textiles in an aqueous wash bath. In particular it relates to a method of facilitating the flow of water out of clothing and textiles during the final rinse stage of the laundering cycle by using small amounts of amidoalkyl-containing polydiorganosiloxane in the rinse bath.
Automatic clothes washing machines employ a variety of wash cycles with a number of machine stages which usually include an agitated wash using an aqueous detergent solution, a spin-filter to remove the aqueous detergent solution and soil, an agitated rinse bath to remove residual detergent and soil, and a final spin-filter to remove the aqueous rinse bath. After the final spin-filter stage, the water retained in the clothing and textiles is removed by a drying step which typically includes blowing heated air over the tumbling textiles in a clothes drying machine.
The thermal drying of clothes and textiles is time consuming and requires considerable energy. Consequently, it is an object of the present invention to facilitate the drying of clothes and textiles after laundering by providing a method of washing clothes and textiles wherein the amount of water retained in the fabric after the final spin-filter, is reduced.
It has been known for a long time to employ fabric conditioning compositions in the rinse step of textile laundering to confer on textiles such well-known benefits as softening, anti-wrinkling, smoothness, ease-of-ironing, whitening and perfuming. The active softening ingredient is usually selected from the group of cationic and/or nonionic fabric substantive agents. Well-known cationic fabric softening agents include the organic quaternary ammonium compounds having either one or two higher alkyl substituents such as ditallowdimethylammonium chloride and tallowtrimethylammonium chloride. Nonionic softening actives include polyethoxylates, fatty acid esters, paraffins, fatty alcohols and fatty acids.
Great Britain Patent Specification No. 1,549,180 further teaches fabric conditioning compositions comprising a combination of organic cationic fabric-softening agents and certain types of silicone materials. The combination is reported to provide a very desirable softening effect and such additional benefits as ease-of-ironing for the textile. The Great Britain patent also teaches that if normal commercial silicones are applied to fabrics from dilute aqueous systems, they are not substantive to a useful degree, in that insufficient silicone is present in the dilute residual liquor in the fabric to provide any appreciable effect. On the other hand, it is taught that the silicone in the presence of the organic cationic agent tends to migrate with the organic cationic agent to the surface of the fabric where it is sufficiently concentrated to provide fabric conditioning benefits. Silicones with cationic character such as the hydrochloride salt derivative of polydimethylsiloxane substituted with dimethylaminopropyl groups are included among the types of silicone employed with the organic cationic fabric-softening agent.
U.S. Pat. No. 4,247,592 teaches a method for treating synthetic textiles with aminoalkyl-containing polydiorganosiloxanes to provide a crosslinked siloxane on the surface of the treated fiber without diminishing the fire-retardancy rating of the fibers. It is taught specifically that appropriate polydiorganosiloxanes contain an average of up to 100 dimethylsiloxane units and two nitrogen-containing siloxane units per molecule, where the nitrogen-containing siloxane units have a substituent such as --CH.sub.2 CH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 NH.sub.2. It is further taught that the "hand" of nylon fabric can be improved by adding specified polydiorganosiloxanes to the rinse water while washing the fabric in an automatic clothes washing machine.
Amidofunctional siloxane polymers containing substituents such as ##STR1## attached to silicon are described in U.S. Pat. No. 3,440,261. The amidofunctional siloxanes are reported generally to be useful as coupling agents for the preparation of glass cloth-resin laminates and as textile treating agents to improve the dyeability of the textile with acid dyes. Amido-functional siloxane polymers are further described in U.S. Pat. No. 4,507,455 which is commonly owned with the present application. The use of amidofunctional siloxanes as mold release and hair conditioning agents is described in this patent.
Copending U.S. patent application Ser. No. 737,592 which is commonly owned with the present application, describes a fabric softener composition containing a blend of a conventional, cationic organic softening agent and a polydiorganosiloxane having an amidofunctional substituent of the formula ##STR2## Fabric softener compositions are employed during the rinse or drying cycle of a laundry operation to improve the softness of hand of the laundered fabric.
None of the above references suggest in any way that polydiorganosiloxanes can be used during textile laundering to improve the draining of water out of the textiles during the final rinse step. However, in another art area, U.S. Pat. No. 4,290,896 teaches that a wide variety of silicone materials can be used in fine coal dewatering processes to improve the separation of water from the coal. Among the silicone materials described in this reference is a polydiorganosiloxane containing 98 dimethylsiloxane units and 2 siloxane units having --CH.sub.2 CH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 NH.sub.2 as a substituent.
Applicants' copending U.S. patent application Ser. No. 718,403 teaches the use of aminofunctional silicones to improve the draining of water out of textiles during laundry operations.